Organic stripper, radiation decontaminant, passivator and rust remover



United States Patent 3,391,084 ORGANIC STRTPPER, RADIATION DECON- TAMINANT, PASSIVATOR AND RUST REMOVER Emil J. York, Annandale, Va., assignor to the United States of America as represented by the Secretary of the Army No Drawing. Continuation-impart of application Ser. No. 230,624, Oct. 23, 1962. This application Oct. 21, 1965, Ser. No. 500,390

4 Claims. (Cl. 252-437) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental .purposes without the payment to me of any royalty thereon.

This application is a continuation-in-part of my copending application Ser. No. 232,624 filed Oct. 23, 1962 for Organic Stripper, Decontaminant, Phosphatizer and Rust Remover, now abandoned.

This invention relates to improvements in organic strippers, radiation decontaminants, passivators and rust removers. More specifically, this invention relates to a thixotropic mixture of substances that accomplishes rapid organic stripping, radiation decontamination, passivating and rust removing.

Prior materials of the type set forth by this invention are variously deficient in the following characteristics. There is no package stability, that is, the effectiveness of the material is lost during storage. The prior materials are stored in expensive containers to minimize storage losses. The prior materials do not remove all types of organic films, but are selective. The residuals left on the substrates required extra steps to be removed. The chem ical action of prior materials cause hydrogen embrittlement which also changes the physical characteristics of the substrate. The prior materials are expensive along with the other deficiencies. They are further, ineffective on epoxy films nor do they remove radioactive substances. The viscosities of various of the prior strippers are not conductive to good application as demonstrated by sagging and running. Carbon deposits are left on the substrate. Rinsing of the prior strippers is not sufficient to remove all of the film from the substrate as well as the residues. Also lacking is passivation, such as phosphatizing, to reduce oxidation problems. It was the awareness of the inadequacy of the prior art that prompted this inventor to invent his novel emulsion that is free of all of the above listed deficiencies.

It is therefore, an object of this invention to provide a material which causes a chemical removal of thermosetting plastics or coatings in minutes and which at the same time removes radiation contaminants and superficial rust.

It is also an object of this invention to provide in an organic stripper, a nonfiammable, water rinsible, solvent type material which is suitable for removing dry paint from all types of metallic and nonmetallic substances, such as nitrocellulose lacquer from wood or metal, oil base paints from gypsum board without destroying the characteristics of the gypsum board, organic films from aluminum without causing deleterious effects to the aluminum.

A further object'of this invention is to remove carbon residuals, that is no smut remains after the use of this material.

Another object of this invention is to prepare a thixotropic emulsion that can be applied by roller, spray or brush on either vertical or horizontal surfaces.

A still further object of this invention is to provide a surface on the substrate with no hydrogen embrittlement. The physical structure of the substrate is not affected. Even the grain of wood is not caused to rise.

Still another object of this invention is to provide a 3,13%,934 Patented July 2, 1968 stripper which not only removes organic films from metals but also deposits :1 phosphate or the like, ion on the clean metal substrate. Oxidation of the metal is prevented as passivation is accomplished.

Other objects of this invention are to provide in an organic stripper, radiation decontaminan't, passivator and rust remover, a material capable of being easily mixed to a homogeneous condition of such consistency that a heavy coating may be applied without tendency to drain, of minimum evaporation, of package stability, having a minimum of corrosiveness, having storage stability and having a minimum of toxicity.

It is therefore, an object of this invention to remove all of the deficiencies of the prior art materials.

Further object will be seen from the detailed specification following hereafter.

I have found that certain combinations of chemicals can be combined to produce a material which can be applied by roller, spray or brush application on previously painted and plastic coated and/ or plastic surfaces, causing, in a few minutes, the organic film to blister and soften. These blisters are caused by the formation of gas pockets between the film and the substrate. This film can then be flushed off with water; and where the film is flushed off ferrous or steel substrates, no film nor residue is left on the substrate. Only a passivated coating remains. When the metal is dry it may be repainted. It is important to note that no surface preparation is necessary.

This same material can be brushed or sprayed on metallic or nonmetallic substrates for use as a decontaminant. This material has been used successfully to remove paint and reduce radioactive count on warehouse walls to a level to which humans can be safely exposed.

The packaging of this emulsion presents no problems as to rusting of conventional containers. No breakdown in the efficiency of the material has occurred in storage tests that have run for a year now. The emulsion has maintained its original properties at the end of a year of shelf storage.

Superficial rust from cold and hot rolled steel can be removed without scrubbing or wire brushing. Superficial rust can be removed from ferrous substrates simply by applying this material by brush or spray on the surface and allowing it to remain for from 5 to 10 minutes. A soft brush, previously soaked in water, can then be used to scrub off the rust. When the substrate is later flushed off with water, only a phosphate coating is deposited, thus preventing further rusting.

It has also been found that. these materials remove epoxy type compounds within ten minutes.

The following examples illustrate the: invention:

Example 1 This stripper is a composite mix of the following chemicals:

Percent by weight Methylene chloride, 370 grams 71 Paratfin wax, household type, 2.25 grams .4 Methyl cellulose, high viscosity, 6.25 grams 1.1 Sodium alkyl aryl sulfonate, active, 25 grams 5.0 Methanol, 31 grams 6.0 Butyl alcohol, 6 grams 1.1 Ethylene glycol monoethyl ether, 22 grams 4.0 Monoethlylamine, anhydrous, 23.5 grams 4.1 Sodium phosphate, 12 grams 2.2 Ethylenediaminetetra acetic acid, 10 grams 2.0 Water, 16 grams 3.1

In mixing the above, glass or plastic lined containers should be used. The wax is first dissolved into the methylene chloride by heating at least a hundred grams of the methylene chloride slightly, and then adding the wax. The

remainder of the methylene chloride is then added. The methyl cellulose is then added with strong agitation, followed by mixing for from to 7 minutes. The alkyl aryl sodium sulfonate is then added with strong agitation. The methanol, butyl alcohol and ethylene glycol monoethyl ether are then mixed and added slowly to the previously described mixture using strong agitation. The sodium phosphate is dissolved into the water and the ethlenediaminetetra acetic acid is added to the sodium phosphate. This sodium phosphate-ethylenediaminetetra acetic acid mixture is then added slowly to the previously described batch using strong agitation. The entire stripper is then mixed well for about ten minutes, resulting in a stable, thixotropic emulsion.

The methylene chloride acts as a fire retardant and a true solvent for stripping organic coatings and as the solvent for the low melting point wax. The wax, when in solution has a tendency to float to the top after applying the compound thus retarding the low boiling point solvents from evaporating too rapidly. The methyl cellulose is used in this formula as a dispersing, adhesive and emulsifying agent. The sodium alkyl aryl sulfonate acts as a wetting, emulsifying agent. The methyl cellulose and the sodium alkyl aryl sulfonate allow the compound to adhere to and penetrate a dried paint; allowing it then to be flushed readily off by emulsifying the excess water and the compound. The function of the methanol is to swell and dissolve the methyl cellulose. The butyl alcohol retards evaporation, it being a high boiling point solvent. The ethylene glycol monoethyl ether acts as a booster for the methylene chloride. Methylene chloride, if prevented from fast evaporation, will normally remove paint and plastics relatively slowly. With the help of the ethylene glycol monethyl ether this removal time is cut in half. The monoethylamine, combined with the alcohols in the com pound acts as a stabilizer and is the gas producing ingredient. After the compound penetrates the organic film the above ingredient releases a large volume of gas which raises blisters 'on the coating. These blisters form between the paint film and the metallic substrate. The ethylenediaminetetra acetic acid combines with any radio active material (such as lead 208, forming lead acetate). When the substrate is flushed with water the radio active material is thereby removed. The function of the sodium phosphate is to provide a phosphate coating on the substrate after it has been cleaned thus preventing the substrate from oxidizing prior to repainting. Water keeps the sodium phosphate methyl cellulose and sodium alkyl sulfonate in suspension helping to provide a complete and stable emulsion of the material.

The sodium alkyl aryl sulfonate disclosed in Example 1 can be the product sodium dodecylbenzene sulfonate sold under the trademark Nacconol by National Aniline Division, Allied Chemical Corporation in many strengths. That is, C H C H SO Na shown as l Alkyl chain] Q-smm The aryl substituent may be naphthalene whereas the alkyl group usually is a straight chain having to carbons. Branching and multiple substitution on aryl ring reduce detergent action.

Experimentation has shown that acceptable tolerances in quantities of the mixture of Example 1 are as follows:

Grams Methylene chloride 300-370 Paraflin wax 1-2.25 Alkyl aryl sulfonate 15-25 Methyl cellulose 5-6.5 Sodium phosphate 7-12 Ethylene glycol monoethyl ether 15-22 With respect to Example 1 it has been found that the following substitutions can be made for the materials listed. Nitromethane, nitroethane or dimcthyl acetamide may be substituted for methylene chloride, Sorbitan monostearate or beeswax Fahrenheit, melting point) may be substituted for parafiin wax. Casein and starch may be substituted for methyl cellulose. Sodium chromate may be substituted for sodium phosphate; and ethylene glycol monomethyl ether may be substituted for the ethylene glycol monoethyl ether.

The materials and the amounts set forth in Example 1 are critical in that the properties of this invention are significantly altered by variations thereof. For example, too much methylene chloride would react with the amine compound upon aging to form crystals which would render the material ineffective in use. Too much paraflin would provide a scum or a residue which would be very difiicult to remove. Too much sodium alkyl aryl sulfonate would produce too much foaming and too many s-uds. Too much monoethylamine anhydrous the corrosive characteristics of the emulsion. Too much water would break up the emulsion to destroy its thixotropic characteristics. Further, too little sodium alkyl aryl sulfonate would result in poor cleaning characteristics, too little water would give improper viscosity control for vertical as well as horizontal application. Too little alcohol would cause the emulsion to dry too rapidly.

In order to prepare the thixotropic emulsion of this invention, the method steps set forth earlier in this specification are critical. To attempt to prepare the mixture otherwise would result in the loss of one or more of the desirable characteristics of this emulsion. For example, the thixotropic property would be lost should the ingredients simply be mixed haphazardly.

Example 2 This organic stripper is composed as follows:

Percent by weight The wax is heated in a small portion of the methylene chloride. When the wax is completely dissolved the remainder of the methylene chloride is added. The methyl cellulose is added to the above, stirring constantly. The dioctyl sodium sulfosuccinate is dissolved in methyl alcohol and the ethylene glycol monoethyl ether, this being added to the above described batch with strong agitation. The bis (2 chlor ethyl) ether is added with strong agitation. The monoethylamine is added with strong agitation. Water is added slowly, again with strong agitation.

Acceptable tolerances in the preparation of the stripper described in Example 2 are as follows:

Percent by Weight Methylene chloride 72-76 Paraflin wax 0.61 Methyl alcohol 5-6 Methyl cellulose 1.22-3.7 Dioctyl sodium sulfosuccinate 1.5-2

The materials and the amounts set forth in Example 2 are critical in that the properties of this invention are significantly altered by variations thereof. For example, too much sodium phosphate would precipitate out. Too much dioctyl sodium sulfosuccinate provides thesame result as too much sodium alkyl aryl sulfonate in Example 1, that is, too much foaming and too many suds. Too much his (2 chlor ethyl) ether would lower the e-fficiency of stripping, where too little would cause the emulsion to dry too rapidly. Variation of similar ingredients in the two examples would give the same results to either example.

Equivalent substitutions for methylene chloride and for paraffin wax are the same as those described for Example 1. Ethyl alcohol may be substituted for methyl alcohol. Casein may be substituted for methyl cellulose; and Aerosol C61 may be substituted for dioctyl sodium sulfosuccinate. Aerosol C61 is a material trade-name of American Cyanamid Company representing an ethanolated alkyl tguanidine-amine complex shown as:

NH Alkyl Chain It is a new type of cationic surface-active agent containing approximately 30% active ingredients in isopropyl alcohol and water.

An example of the effectiveness of the material disclosed in this application is shown by the application of this material to the walls of a metal dome surrounding an atomic reactor. The five year old phenolic-zinc dust coating on the dome Wall had a thickness of old paint 9 to 11 mils over an area of 10,000 square feet. The material of this invention was applied by brush over the old coating. Within three minutes the paint started to bubble. All the old paint was removed within 4 days. This time would have been considerably shorter had there not been a specified time limit for personnel to remain in the reactor. Nevertheless, the use of this material shortened the shut down time of the reactor by approximately 2 weeks. That is, cleaning and repainting time was reduced from approximately 18 days to 4 days. Sand blasting and the use of other prior art strippers proved ineffective. The use of the material of this invention is now standard operating procedure for the cleaning of all military reactors.

Unlike acid or alkali strippers both formulas produce materials that do not attack steel, stainless steel, cast or malleable irons, and aluminum; nor do they cause carbon smut, smut formation thereby inhibiting the work against flash rusting during rinsing. Acid fumes are nonexistent and corrosion of surrounding equipment is eliminated. Hydrogen embrittlement of steel is also eliminated because there is no attack of steel substrates with the accompanying hydrogen gas evolution.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood, that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. The process of producing an organic stripper, decontamin-ant, passivator and rust remover emulsion comprising the steps of preparing a first mixture by melting paraffin wax which constitutes 1 percent by weight of the emulsion and dissolving said wax in methylene chloride which constitutes 74 percent by weight of the emulsion, mixing with said wax and said methylene chloride methyl cellulose 4000 centipoises, which constitutes 1.2 per-cent by weight of the emulsion with strong agitation for about seven minutes until the methyl cellulose swells; preparing a second mixture by dissolving dioctyl sodium sulfosuccinate which constitutes 2 percent by weight of the emulsion in methyl alcohol which constitutes 6 percent by weight of the emulsion and in ethylene glycol monoethyl ether which constitutes 4.1 percent by weight of the emulsion with strong agitation for about seven minutes; mixing said first and second mixtures with strong agitation to produce a third mixture; dissolving bis (2 chloro ethyl) ether which constitutes 3.9 percent by weight of the emulsion in said third mixture with strong agitation to produce a fourth mixture; combining monoethylamine gas which constitutes 4.6 percent by weight of the emulsion with the fourth mixture with strong agitation; and dissolving water which constitutes 3.2 percent by weight of the emulsion slowly with strong agitation to produce a stable emulsion.

2. The process of producing an organic stripper, radiation decontaminant, passivator and rust remover emulsion comprising the steps of preparing a first mixture by melting parafiin wax which constitutes .4 percent by Weight of the emulsion and dissolving said wax in methylene chloride which constitutes 71 percent by weight of the emulsion, preparing a second mixture of methyl cellulose which constitutes 1.1 percent by weight of the emulsion with sodium alkyl aryl sulfonate which constitutes 5 percent by weight of the emulsion and methanol which constitutes 6 percent by weight of the emulsion, combining said first and second mixtures 'to form a third mixture, preparing a fourth mixture of butyl alcohol which constitutes 1.1 percent by weight of the emulsion and ethylene glycol monoethyl ether which constitutes 4 percent by weight of the emulsion, combining said third and fourth mixtures to form a fifth mixture, by combining sodium phosphate which constitutes 2.2 percent by weight of the emulsion, ethylenediaminetetra acetic acid which constitutes 2 percent by weight of the emulsion and water which constitutes 3.1 percent by weight of the emulsion, combining said fifth and sixth mixtures and blending therewith anhydrous monoethylamine which constitutes 4.1 percent by weight of the emulsion and mixing until a stable emulsion is obtained.

3. A process for the production of an organic stripper, and rust remover comprising the steps of: heating until melted a material which constitutes about .6-1 percent by weight selected from the group consisting of paraffin wax, beeswax and sorbitol monostearate, dissolving said melted material in a material which constitutes 72-76 percent by weight selected from the group consisting of methylene chloride, dimethyl acetamide, nitroethane and nitromethane with strong agitation; adding a material which constitutes 1.2-3.7 percent by weight selected from the group consisting of methyl cellulose and casein with strong agi tation; dissolving a material which constitutes 1.5-2 percent by weight selected from the group consisting of dioctyl sodium sulfosuccinate and an ethanolated alkyl guanidine-amine complex, in a material which constitutes 5-6 percent by weight selected from the group consisting of methyl alcohol and ethyl alcohol; dissolving a material which constitutes 4.1 percent by weight selected from the group consisting of ethylene glycol monoethyl ether and ethylene glycol monomethyl ether in said material selected from the group consisting of methyl alcohol and ethyl alcohol; combining said two said dissolved mixtures with strong agitation; adding bis (2 chloro ethyl) ether which constitutes 3.9 percent by weight with strong agitation; adding monoethylamine which constitutes 4.6 percent by weight with strong agitation; and adding water with strong agitation to form a stable emulsion.

4. The process of producing an organic stripper, decontaminant, passivator and rust remover comprising the steps of heating until melted a material which constitutes about .4 percent by weight selected from the group consisting of parafiin wax, beeswax and sorbitol monostearate and dissolving said melted material which constitutes about 71 percent by weight into a material selected from the group consisting of methylene chloride, dimethyl acetamide, nitroethane and nitromethane with strong agitation; adding a material which constitutes about 1.1 percent by weight selected from the group consisting of methyl cellulose and casein with strong agitation; adding alkyl aryl sodium sulfonate which constitutes about 5 percent by weight with strong agitation; adding a mixture of methanol which constitutes about 6 percent by weight, butyl alcohol which constitutes about 1.1 percent by weight and a material which constitutes about 4 percent by weight selected from the group consisting of ethylene glycol monoethyl ether and ethylene glycol monomethyl ether with strong agitation; adding anhydrous monoethylamine which constitutes about 4.1 percent by weight with strong agitation; adding a mixture of a material which constitutes about 2.2 percent by weight selected from the group consisting of sodium phosphate and sodium chromate with Water and with ethylenediaminetetra acetic 15 acid which constitutes about 2 percent by weight with strong agitation; and mixing thoroughly to form a stabilized emulsion.

References Cited UNITED STATES PATENTS Baum et al.

Othmer 252-171 Kuentzel 252-154 Hutson et al 252-161 Mankowich 252-137 Bersworth et a1, 2. 252-137 XR Sims 252-170 XR Greminger et al. 252-170 XR OTHER REFERENCES Bennett, The Chemical Formulary, vol. 10, Chem. Publ. Co., Inc. (1957), pp. 252-253 relied on.

LEON D. ROSDOL, Primary Examiner. W. E. SCHULZ, Assistant Examiner. 

1. THE PROCESS OF PRODUCING AN ORGANIC STRIPPER, DECONTAMINANT, PASSIVATOR AND RUST REMOVER EMULSION COMPRISING THE STEPS OF PREPARING A FIRST MIXTURE BY MELTING PARAFFIN WAX WHICH CONSTITUTES 1 PERCENT BY WEIGHT OF THE EMULSION AND DISSOLVING SAID WAX IN METHYLENE CHLORIDE WHICH CONSTITUTES 74 PERCENT BY WEIGHT OF THE EMULSION, MIXING WITH SAID WAX AND SAID METHYLENE CHLORIDE METHYL CELLULOSE 4000 CENTIPOISES, WHICH CONSTITUTES 1.2 PERCENT BY WEIGHT OF THE EMULSION WITH STRONG AGITATION FOR ABOUT SEVEN MINUTES UNTIL THE METHYL CELLULOSE SWELLS; PREPARING A SECOND MIXTURE BY DISSOLVING DIOCTYL SODIUM SULFOSUCCINATE WHICH CONSTITUTES 2 PERCENT BY WEIGHT OF THE EMULSION IN METHYL ALCOHOL WHICH CONSTITUTES 6 PERCENT BY WEIGHT OF THE EMULSION AND IN ETHYLENE GLYCOL MONOETHYL ETHER WHICH CONSTITUTES 4.1 PERCENT BY WEIGHT OF THE EMULSION WITH STRONG AGITATION FOR ABOUT SEVEN MINUTES; MIXING SAID FIRST AND SECOND MIXTURES WITH STRONG AGITATION TO PRODUCE A THIRD MIXTURE; DISSOLVING BIS (2 CHLORO ETHYL) ETHER WHICH CONSTITUTES 3.9 PERCENT BY WEIGHT OF THE EMULSION IN SAID THIRD MIXTURE WITH STRONG AGITATION TO PRODUCE A FOURTH MIXTURE; COMBINING MONOETHYLALMINE GAS WHICH CONSTITUTES 4.6 PERCENT BY WEIGHT OF THE EMULSION WITH THE FOURTH MIXTURE WITH STRONG AGITATION; AND DISSOLVING WATER WHICH CONSTITUTES 3.2 PERCENT BY WEIGHT OF THE EMULSION SLOWLY WITH STRONG AGITATION TO PRODUCE A STABLE EMULSION. 